Abstract: The interface zone ofMg/Al diffusion-bonded joint is constituted with Al transition layer (Mg₂Al₃ phase), middle diffusion layer (MgAl phase)and Mg transition layer (Mg₃Al₂ phase). Some diffusion holes exist between the Al transition layer and middle diffusion layer observed by SEM.It is unfavorable to obtain diffusion- bonded joint of good performance.With the increase of heating temperature, the shear strength of joint interface shows the trend of increasing firstly and then decreasing.The highest shear strength is about 18.94MPa when the heating temperature is 475℃, holding time is 60 min and pressure is 0.081 MPa.The microhardness test indicated that the microhardness of diffusion zone is about 260-350 HM.However, and the diffusion zone exist three different hardness regions.With the increase of heating temperature, the microhardness and diffusion width of interface diffusion zone increase gradually.